This dissertation is interested in the connection between romano-persian political relations and the way written sources presented the Sassanids during late antiquity. Antique tradition had indeed been quite biased towards the Orientals: Persians in particular are usually described as cruels, cowardly, effeminates, lazy, toady and treacherous. Are these topoi, noticeable from the 5th century B.C., evolving during the 4th-6th centuries A.D., when the Sassanid kingdom is causing so many problems on the eastern frontier? Using anthropological tools and up-to-date publications on alterity and ancient ethnography, this essay strives to attain a better understanding of the Romans through the study of the way they presented their neighbors.